Method of making thermoplastic composite layered squeeze tube

ABSTRACT

A thermoplastic tube, and method for forming such a tube, has a tube body portion formed from an inner layer of thermoplastic material, a barrier layer, and an outer layer of thermoplastic material. The outer layer does not extend completely about the periphery of the tube body and a strip of thermoplastic material having the same composition as the inner layer, fills each gap in the outer layer to form a smooth surface about the tube. The strip may be transparent or of a color different than the color of the outer layer. In a preferred tube, a first layer of adhesive material is provided between the inner layer and the barrier layer, and a second layer of adhesive material is provided between the barrier layer and the outer layer and strip.

This is a division of application Ser. No. 07/928,250 filed Aug. 10,1992 now U.S. Pat. No. 5,238,148 issued Aug. 24, 1993.

FIELD OF THE INVENTION

The present invention relates to a thermoplastic tube formed from anextruded multi-layer tubular cylinder, which tube has at least one stripalong the tube, in the axial direction of the tube, which is of adifferent transparency or color than the remainder of the tube.

BACKGROUND OF THE INVENTION

Thermoplastic tubes in the form of squeeze tubes have been commerciallyavailable for use in the packaging of toothpaste, shampoo, cosmetics,foodstuffs, and the like. Such tubes may be produced by severing a tubeblank from an extruded tubular cylinder, which tube blank has open ends,and forming a head on one end of the tube blank which has a threadedneck or other means for releasably securing a cap on that end of thetube. After filling the capped tube from the other open end, that otheropen end is then sealed, such as by heat sealing, to protect the tubecontents and to complete the filled tube for subsequent sale.

The formation of such thermoplastic squeeze tubes from multi-layeredmaterial, or extruded composites, has been found useful in that abarrier layer may be provided, such as an oxygen impermeable layer,which barrier layer prevents escape of essential oils, or the like, fromthe tube contents, and protects the contents of the tube fromdiscoloration, change in taste, or other detrimental affect of oxygen onthe tube contents. The formation of extruded composite tubular cylindersfor use in forming tube blanks is a known procedure, as for exampledescribed in U.S. Pat. No. 4,723,902, entitled Balanced Flow ExtrusionCrosshead and Die Assembly, assigned to the assignee of the presentinvention, the contents of said patent incorporated by reference herein.As described, such tubes generally have five layers which compriseinnermost and outermost layers of a thermoplastic material, a centrallayer of a barrier polymeric material, and adhesive polymeric materiallayers, one between the innermost thermoplastic layer and the barrierlayer and the other between the outermost thermoplastic layer and thebarrier layer. In some instances, where the inner and outer layersadhere sufficiently themselves to the barrier layer, the separateadhesive layers may not be necessary, and a three layered extrudedcomposite tube may be provided.

Such thermoplastic multi-layered tubes have been readily accepted andhave been provided with various decorative features and indicia.Indicia, decorative features, and printed matter may be applied tothermoplastic tubes by hot stamping or dry printing, or application of afoil pattern to the tube outer surface. When the thermoplasticmulti-layered tube is formed from transparent or translucent material,the tube contents of the tube are visible to the user, but readabilityof the printed matter on the tube may be less than desired due to theclear background. Or, when the tube has a colored component as one ofthe layered materials of the multi-layered tube, the readability of theprinted matter can be enhanced, but the tube contents are no longervisible to show the amount of contents remaining after partial use by apurchaser. Also, the added step of providing decorative featuresincreases the cost of the tube.

It is an object of the present invention to provide a thermoplasticcomposite layered tube that has at least one strip of material along thelength of the tube that is either transparent, while the remainder ofthe tube is non-transparent, or is of a color different from the colorof the remainder of the tube.

It is another object of the present invention to provide a method offorming a thermoplastic composite layered tube that has at least onestrip along the length of the tube that is either transparent, while theremainder of the tube is non-transparent, or is of a different colorfrom the color of the remainder of the tube, during the tubemanufacturing process, without the subsequent need to apply ink or foilalong the length of the tube.

SUMMARY OF THE INVENTION

The thermoplastic composite layered tube of the present invention has atube body portion formed as a multi-layered hollow cylindrical bodyhaving a longitudinal axis. The tube body portion has an inner layer ofthermoplastic material, such as polyethylene, a barrier layer, such asan ethylene polyvinyl alcohol polymer, and, superimposed partially overthe barrier layer, an outer layer of a thermoplastic material, such aspolyethylene, in a manner that provides at least one gap in the outerlayer in a direction parallel to the longitudinal axis of the tube bodyportion, and a strip of thermoplastic material, of a material the sameas the material of the inner layer is provided filling each gap. A headis formed on one end of the tube body portion, the head having anorifice for squeezing contents of the tube therefrom, and a cap isreleasably secured to the head to close the orifice. Upon filling thetube with contents, the end of the tube body portion opposite the headis sealed, such as by heat sealing.

In one embodiment of the present tube, the inner layer of thermoplasticmaterial, the barrier layer, and the strip of thermoplastic material aretransparent, while the outer layer of thermoplastic material isnon-transparent thus providing a strip of transparency along the tubebody portion. In such an embodiment, the outer layer of thermoplasticmaterial may be either opaque or colored.

In another embodiment of the present tube, at least one of the innerlayer, the barrier layer, or strip of thermoplastic material are of afirst color, while the outer layer of thermoplastic material is of adifferent color. In such an embodiment, a strip of material of a colordifferent from the color of the remainder of the tube is thus provided.

In a preferred embodiment of the present tube, a five layered,multi-layered tube body portion is provided, with a first adhesive layerprovided between the inner layer and the barrier layer, and a secondadhesive layer provided between the barrier layer and the outer layerand strip of thermoplastic material of a material the same as thematerial of the inner layer.

The method according to the present invention involves extruding aspecific multi-layered cylinder having a longitudinal axis, severing atube blank from the extruded cylinder, forming a head on one end of thetube blank having an orifice therethrough, and releasably securing a capon the head. The multi-layered cylinder formed on extrusion has an innerlayer of thermoplastic material, a barrier layer on the inner layer, andan outer layer of thermoplastic material superimposed over a portion ofthe barrier layer, and at least one strip of thermoplastic material thesame as the inner layer so as to provide a strip parallel to thelongitudinal axis of the multi-layered cylinder. Preferably, thecylinder formed on extrusion has a first adhesive layer between theinner layer and the barrier layer, and a second adhesive layer betweenthe barrier layer and the outer layer of thermoplastic material, and thestrip of thermoplastic material the same composition as the inner layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be explained with reference to theaccompanying drawings wherein like numerals indicate like partsthroughout the drawings, and wherein:

FIG. 1 is a front elevational view of a five layered tube of the presentinvention having a single strip;

FIG. 2 is a cross-sectional view taken along lines II--II of FIG. 1;

FIG. 3 is a view taken along lines III--III of FIG. 2;

FIG. 4 is a view taken along lines IV--IV of FIG. 2;

FIG. 5 is a plan view of an extruded multi-layered cylinder with a tubeblank severed therefrom;

FIG. 6 is a schematic illustration of an extruder crosshead with thesequential feeding of materials to form a five layered extrudedmulti-layered cylinder from which tube blanks are cut; and

FIG. 7 is a front elevational view of a three layered tube of thepresent invention, having a plurality of strips, after filling the tubeand sealing the end of the tube body opposite the head on the tube body,with a cut away section showing the layers.

DETAILED DESCRIPTION

The thermoplastic composite layered tube of the present invention isformed from a tube blank cut from an extruded multi-layered cylinder.Referring now to the drawings, which illustrate a single strip along atube, although it is understood that a plurality of such strips may beprovided, a thermoplastic composite layered tube 1, having five layers,is illustrated in FIGS. 1-4 prior to filling of the tube with thedesired contents and sealing of the end of the tube opposite the end towhich a head has been secured. A head 5 is secured to one end of thetube body portion 3, the head 5 having an orifice 7 formed therethroughand means 9 thereon for releasably securing a cap thereto, such asthreads 11. The other end 13 of the tube body portion 3 is open, untilthe contents of the tube are changed thereto and the open end 13 is thensealed such as by heat sealing.

The tube body portion 3 is formed as a multi-layered hollow cylinderhaving a longitudinal axis a. The five layered tube body portion 3, hasan inner layer of thermoplastic material 15 that is adapted to contactthe tube contents 17 after the thermoplastic composite layered tube 1has been filled. Superimposed over and adhered to the inner layer ofthermoplastic material 15 is a first adhesive layer 19 which completelysurrounds the inner layer 15. Superimposed over and adhered to the firstadhesive layer 19 is a barrier layer 21, such as an oxygen-impermeablethermoplastic polymer, which barrier layer completely surrounds thefirst adhesive layer 19. On the side of the barrier layer 21 oppositethe first adhesive layer, there is superimposed and adhered a secondadhesive layer 23, which second adhesive layer 23 completely surroundsthe barrier layer 21. Finally, an outer layer 25 of thermoplasticmaterial is superimposed over and adhered to the second adhesive layer23, which outer layer 25, however, is superimposed over only a portionof the second adhesive layer 23. As shown, a gap 27 is provided betweenopposite ends 29 and 31 of the outer layer 25 of thermoplastic material,and a strip of thermoplastic material 15', of the same composition asthe inner layer of thermoplastic material 15, which has been extrudedalong with the outer layer 25, is adhered to the second adhesive layer23 and welded to the ends 29, 31 of the outer layer of thermoplasticmaterial 25. The outer layer 25 of thermoplastic material and the stripof thermoplastic material 15' combine to form a substantially smoothouter surface along the tube body portion 3.

The inner layer 15 of thermoplastic material may be composed, forexample, of high density polyethylene, low density polyethylene,polypropylene, or a polyester such as polyethylene terephthalate. Thebarrier layer 21 may comprise various low-gas permeable polymericmaterials, for example oxygen-impermeable polymeric materials such aspolyamides, such as nylon, ethylene polyvinyl alcohol polymers, or apolyvinylidene chloride and copolymers containing a major portion ofpolyvinylidene chloride. The first and second adhesive layers 19 and 23are known polymeric compositions that adhere various thermoplasticlayers to barrier layers, such as ethylene vinyl acetate copolymers,ethylene ethyl acrylate copolymers, and the like.

The strip of thermoplastic material 15', shown as a single strip,although a plurality of each strip may be provided, which overlays thesecond adhesive layer 23 is of the same composition as the inner layer15 of thermoplastic material, while the outer layer 25 of thermoplasticmaterial may comprise the same polymeric material but will be acomposition that is different from the strip of thermoplastic material15'. For example, the inner layer 15 and strip 15' may comprise a clearpolyethylene material, while the outer layer 25 would comprise apolyethylene material containing a colorant. Or, the inner layer 15 andstrip 15' may comprise a clear polyethylene material, while the outerlayer 25 would comprise a blend of high density and low densitypolyethylenes which form an outer opaque layer. In addition, onecolorant could be added to either the inner layer 15 and strip 15' orthe barrier layer, while the outer layer 25 could contain a distinctcolorant, so as to produce a colored stripe down the length of the tubedifferent from the remainder of the tube body.

The thicknesses of the various layers and the overall thickness of thewall of the composite layered tube will vary dependent upon the size ofthe tube and the end use to which the tube is to be put. Typically, theinner layer would be between 0.004-0.007 inch think, preferably about0.005 inch; the barrier layer would be between 0.0005-0.002 inch thick,preferably about 0,001 inch; the first and second adhesive layers wouldeach be between 0.0002-0.001 inch thick, preferably about 0.0005 inch;and the outer layer and strip of thermoplastic material would be between0.008-0.012 inch thick, preferably about 0.010 inch.

According to the method of forming the thermoplastic composite layeredtube of the present invention, a multi-layered cylinder 35 (FIG. 5) isextruded, the cylinder having a longitudinal axis a'. The multi-layeredcylinder is extruded as an inner layer of thermoplastic material, afirst adhesive layer completely surrounding the inner layer, a barrierlayer completely surrounding the first adhesive layer, and a secondadhesive layer completely surrounding the barrier layer. At the sametime as extrusion of the inner layer, two adhesive layers and thebarrier layer, an outer layer of thermoplastic material is extruded overthe second adhesive layer, which outer layer covers only a portion ofthe second adhesive layer, and a gap left between opposed ends of theouter layer is filled with an extruded strip of thermoplastic materialthat has the same composition as the thermoplastic composition of theinner layer, to form a smooth outer surface on the extruded cylinder. Asaforementioned, a plurality of such gaps may be provided, each filledwith an extruded strip of the thermoplastic material of the samecomposition as the inner layer. After extrusion of the multi-layeredcylinder 35, a tube blank 37, which is used as a tube body portion 3, issevered from therefrom. The extrusion sequence is schematicallyillustrated in FIG. 6 for producing a five layered polyethylene tubehaving a white polyethylene outer layer and a clear polyethylene stripalong the length of the tube. As illustrated schematically in anextrusion crosshead assembly, a transparent polyethylene material ischarged to form the inner layer of the cylinder as well as thetransparent strip overlying the second adhesive material. A clearbarrier material and clear adhesive materials are also used. The outerlayer comprises a white polyethylene material which overlies the secondadhesive layer, except for the area covered by the thermoplastic stripso as to produce a tube having a white body portion with a transparentstrip along the length thereof.

After severing, the tube blank, which forms a body portion 3, has a head5 formed thereon, which closes one end of the tube blank. The headgenerally has threads or other means thereon for releasable securementof the cap, and an orifice is provided through the head to exudecontents of a filled tube by a user. The head may be formed by knownmeans, such as, for example, the methods described in U.S. Pat. No.3,047,910 to Downs, or U.S. Pat. No. 5,069,856 to Holoubek and Rhoades,the contents of said two patents incorporated by reference herein.

In some tubes, the tube body portion 3 may be formed as a multi-layeredhollow cylinder having three layers, with the adhesive layers notrequired. In such tubes, an inner layer of thermoplastic material 15would be provided, with a barrier layer 21 superimposed over the innerlayer 15, and an outer layer of thermoplastic material 25 superimposedover only a portion of the barrier layer 21 so as to provide at leastone gap 27 in the outer layer parallel to the longitudinal axis, and astrip of thermoplastic material 15', of the same composition as theinner layer 15 filling each gap 27 to provide a substantially smoothouter surface for the tube body portion.

A three layered tube having a plurality of strips 15', after formationof the head, placement of a cap 39, filling with contents, and sealingof the end 13 opposite the head 5 to form a seal 41, is illustrated inFIG. 7.

The present invention thus provides a thermoplastic composite layeredsqueeze tube with at least one integral strip along the length thereofthat is formed during extrusion of the cylinder from which tube blanksare made, and which strip can be of a different transparency ordifferent color than the remainder of the tube body.

What is claimed is:
 1. The method of forming a thermoplastic compositelayered tube comprising:extruding a multi-layered cylinder with alongitudinal axis, by extruding an inner layer of thermoplasticmaterial, extruding a superimposed barrier layer over said inner layer,and extruding a superimposed outer layer of thermoplastic material overonly a portion of said barrier layer so as to provide at least one gapin said outer layer, between opposed ends thereof, parallel to saidlongitudinal axis, and extruding a strip of thermoplastic material, ofthe same composition as said inner layer, to fill each said gap toprovide a substantially smooth outer surface for said cylinder and forma tube blank; and forming a head on said tube blank, said head havingmeans thereon for releasable securement of a cap thereto.
 2. The methodof forming a thermoplastic composite layered tube as defined in claim 1,wherein said inner layer of thermoplastic material, said barrier layer,and said strip of thermoplastic material are substantially transparentand said outer layer of thermoplastic material is non-transparent. 3.The method of forming a thermoplastic composite layered tube as definedin claim 1, wherein at least one of said inner layer of thermoplasticmaterial, said barrier layer, and said strip of thermoplastic materialis of a first color and said outer layer of thermoplastic material is ofa different color.
 4. The method of forming a thermoplastic compositelayered tube as defined in claim 1 wherein a first adhesive layer isextruded between said inner layer of thermoplastic material and saidbarrier layer, and a second adhesive layer is extruded between saidbarrier layer and said outer layer and said strip of thermoplasticmaterial of the same composition as said inner layer.
 5. The method offorming a thermoplastic composite layered tube as defined in claim 4,wherein said inner layer of thermoplastic material, said barrier layer,said first and second adhesive layers, and said strip of thermoplasticmaterial are substantially transparent and said outer layer ofthermoplastic material is non-transparent.
 6. The method of forming athermoplastic, composite layered tube as defined in claim 5, whereinsaid outer layer of thermoplastic material is opaque.
 7. The method offorming a thermoplastic composite layered tube as defined in claim 5,wherein said outer layer of thermoplastic material is colored.
 8. Themethod of forming a thermoplastic composite layered tube as defined inclaim 4, wherein at least one of said inner layer of thermoplasticmaterial, said barrier layer, said first and second adhesive layers andsaid strip of thermoplastic material is of a first color and said outerlayer of thermoplastic material is of a different color.
 9. The methodof forming a thermoplastic composite layered tube as defined in claim 4wherein said inner layer and strip of thermoplastic material comprise aclear polyethylene material and said outer layer of thermoplasticmaterial comprises a white polyethylene material.
 10. The method offorming a thermoplastic composite layered tube as defined in claim 1wherein said inner layer of thermoplastic material and said strip ofthermoplastic material are provided from a common supply ofthermoplastic material.
 11. The method of forming a thermoplasticcomposite layered tube as defined in claim 1 wherein a plurality of saidgaps are provided in said outer layer, and a strip of said thermoplasticmaterial, of the same composition as said inner layer fills each saidgap.